Tunable multifunctional fish-bone elastic metasurface for the wavefront manipulation of the transmitted in-plane waves

Abstract

In this work, a tunable fish-bone elastic metasurface is used to manipulate the in-plane waves which are more complex than flexural or out-of-plane waves because of the coupling of the P-and SV-waves. First, the refracted generalized Snell's law (GSL) for mixed in-plane wave is deduced which is also testified by the numerical results. Then according to the GSL, the elastic metasurfaces are designed to realize multifunctions such as directional refraction and wave focusing for different working frequencies. The critical refraction is discussed for the directional refraction and the behavior of SV-wave is predicted when the P-wave is designed to focus at any point by the metasurface.

Ultrasonic inspection of near surface defects with additive manufactured metasurface lens

“…Throughtransmission measurement scheme was chosen to show here the focusing behavior where the longitudinal wave dominates. However, simultaneous multi-mode control (Yuan et al, 2020) combining interfaces (Manjunath and Rajagopal, 2019) created by MSL need to be further investigated. The additional attenuation brought by the MSL required a more compact lens design and proper material selection as well.…”

Reconfigurable flexural waves manipulation by broadband elastic metasurface

“…Unlike the previous fish-bone model for which the screws are paralleled to the plate [42,43], in this paper we improve the structure by making the screws perpendicular to the plate which will be more efficient for steering the flexure wave and can facilitate the fabrication of metasurfaces. The calculation models of basic unit and functional element are shown in Figs.…”

“…1(d) demonstrate that the phase shift can cover a 2π period in broadband when s is changed continuously. It should be noticed that the appearance of "sudden changes" in the phase shift nephogram is due to the "phase fold" at f = 2mπ when the phase shift exceeds 2mπ (m = 1, 2, 3…) [42,43].…”

“…And the real time control of a broadband flexural wave was achieved via a programmable metasurface based on the piezoelectric unit and feedback circuit control [41]. Recently, we proposed a fish-bone mechanically reconfigurable elastic metasurface to manipulate the wave front of flexural [42] and inplane waves [43] based on the "screw-and-nut" working principle. By changing the positions of the nuts on the screws, the phase shift of the transmitted wave can be manipulated continuously with high transmittance.…”

Elastic Metagratings with Simultaneous Modulation of Reflected and Transmitted Waves

“…P. Packo et al also proposed a grating structure to achieve anomalous reflection and refraction of flexural waves [34]. Although there are many interesting studies on the modulation of Lamb or SH waves in thin plates with metasurfaces or gratings [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50], in numerous application fields such as non-destructive assessment and structural health monitoring, the complete and simultaneous control of bulk longitudinal and transverse waves are highly desired. In this regard, people utilized plate-like waveguide structures to split the p-wave from SV-wave [51] and achieve abnormal refraction of the SV-wave [52] or used a topology optimization method to obtain anomalous reflection [53] or refraction [54] of a longitudinal wave.…”